FRESNO, Calif. — As an unusual cold spell gripped parts of the West for a fifth day, some California citrus growers reported damage to crops and an agriculture official said national prices on lettuce have started to rise because of lost produce in Arizona.

The extreme chill in the West comes as the eastern U.S., from Atlanta to New York City, is seeing spring-like weather.

In California’s San Joaquin Valley, where farmers are fighting to protect about $1.5 billion worth of citrus fruit on their trees, Sunday temperatures dropped to 25 degrees in some areas and stayed low longer than previous nights.

Prolonged temperatures in the mid-20s or below cause damage to citrus crops.

“It was our coldest night to date,” said Paul Story of Exeter-based California Citrus Mutual, an association of the state’s 3,900 citrus growers. “I think mandarin growers are going to see a range of significant damage, enough that they will have to separate their crops.”

Mandarins are more susceptible to cold than other citrus and start to freeze at about 32 degrees, Story said. Because many mandarin trees were planted in recent years as the fruit’s popularity soared, they are grown in colder areas outside the traditional citrus belt.

Other citrus crops saw little or minimal damage, Story said. This year’s high sugar content in oranges helped protect them, he said, because sugar inhibits freezing.

Growers deployed wind machines to keep the warm air closer to the ground and irrigation to raise the temperature in the groves. Rows farthest away from the protection could be damaged, Story said. And farmers who do not have wind machines could lose crops.

Lindsey-based Robert LoBue — who grows 1,000 acres of citrus, including mandarins — said wind machines were critical in his groves, but saving the crop doesn’t come cheap. LoBue runs one wind machine for every 10 acres and has to employ a crew to operate them.

“We’re very diligent, we run the wind and water all night,” LoBue said, “but we’re spending thousands of dollars to protect these crops.”

And farmers are on the hook for a fifth cold night: a freeze warning remains in effect until 10 a.m. Tuesday for central California.

In Southern California, where strong winds helped keep some crops out of danger by keeping the cold from settling, farmers said any damage would negatively impact workers and consumers.

“We have between 170 to 200 employees and if we can’t pick we have to lay off our picking crews,” said John Gless, a third-generation Riverside-based grower. And if there’s less fruit to pick, he said prices will go up.

Temperatures in downtown Los Angeles fell to 34 degrees, breaking the previous record of 36 degrees set on Jan. 14, 2007.

In Angeles National Forest, where overnight temperatures have been dropping into the 20s, Arcadia hiker Danny Kim, 28, was found Sunday night after surviving 26 hours in the frigid West Fork wilderness. Kim was airlifted to a hospital for treatment of hypothermia.

In Beverly Hills, fans brought heavy coats and scarves as they waited along the red carpet hoping to catch glimpses of stars arriving for the Golden Globes ceremony Sunday evening. Some of the actors shivered but weren’t complaining.

“I’d rather be nippy than boiling hot,” said actress Julia Louis-Dreyfus, who arrived in a strapless dress. “No, I’m not wearing any leggings or long underwear.”

In San Diego, zookeepers offered extra heat and shelter for some animals.

To the east, the freezing temperatures already have done enough damage to southwestern Arizona lettuce crops that prices are increasing, said Kurt Nolte, a Yuma, Ariz.-based agricultural agent for the University of Arizona.

The area provides much of the nation’s leafy greens during the winter, and farmers are reporting damage to many romaine and iceberg lettuce crops. The cold is freezing the heads of the lettuce and affecting the quality and yield, Nolte said.

The price for a carton of lettuce in Yuma two weeks ago was $7 to $8. As of Monday, it cost around $20 per carton, he said.

“That’s a result of cold weather in the Yuma area for the last six weeks,” Nolte said.

Overnight temperatures this week have dipped into the 20s around Yuma, and Nolte said lettuce farmers can’t protect their crops.

“With lettuce, you don’t have the luxury of wind machines to stir up the atmosphere,” he noted. “You have to live with what Mother Nature brings. Very little can be done other than maybe running some water to protect what’s going to be harvested the next day.”

Nolte said Yuma farmers haven’t seen much damage so far with other crops such as spinach, cauliflower and broccoli.

Metropolitan Phoenix marked one of its coolest stretches since 1988 and Sunday morning’s low of 7 degrees in Douglas, Ariz., broke a record for January in the Mexican border town.

Farther north, a school district on the Navajo Nation cancelled all classes Tuesday because of freezing temperatures.

Temperatures in Window Rock, Ariz., were expected to be well below freezing Tuesday with a high of 21 degrees and a low of minus 5 degrees. The Window Rock School District posted the cancellation notice on its website Monday, saying heating the schools has been a problem.

In Nevada, the temperature in Ely plummeted to 24 below zero early Monday and wind chills were expected to drop to near 40 below into Tuesday.

And in northern New Mexico, parts of Interstate 25 and some other highways were snow packed and icy Monday, and officials warned travelers that additional light snow could lead to hazardous driving conditions when coupled with the freezing temperatures.